Readers interested in time theories, astronomy, and cognate
• inatters should not miss the remarkable article by Professor de Sitter in Nature of January 21st. In the years 1897 and again 1918, either suddenly or within a few months, . the period of the earth's rotation altered. In 1910 the difference was -three-hundredths of a second. A collapse of the whole of the Himalayas would not have been disturbance enough to have thus altered the earth's moment of inertia : probably this strange and almost unchronicled change in the world's affairs was due to some cataclysm at its core, some slipping of the masses that lie between us and the nadir, if we understand the Professor rightly. We read also of a free pendulum clock (Shortt 3) installed in Greenwich which keeps accurate time to a few hundredths of a second for a period of years. " If the attraction of the earth remains constant, the clock will keep mathematical time." But if the bowels of the earth grow lively again, literally anything might happen to time hi this age of miracles.
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